A probe for circulating heated water for thawing frozen ground is used in connection with a mobile heating system which is disclosed by co-owned U.S. Pat. No. 5,181,655. The mobile heating system includes a hot water heater, antifreeze reservoir, and pumps mounted on a mobile apparatus such as a trailer for towing by a car or truck. A line is connectable to the heater and antifreeze reservoir and includes a plurality of elongate heater probes for being implanted in the ground adjacent to a frozen water or sewer line. Circulation of hot water through the line and probes thaw the ground. Alternatively, the probes may be used to heat building materials such as bricks.
The mobile heating system which is uniquely adapted for use at construction sites and/or for various ground-thawing purposes is most suitably applied in northern climates. In the northern climates there are a great many uses for a portable or mobile heating system, particularly in the construction industry but also in the maintenance and correction of ground-freezing problems relating to pre-existing structures. A common problem in the northern climate is the problem of frozen underground water and/or sewer pipes. This problem is caused by a combination of factors; in some cases the underground pipes are laid too close to the surface, and in other cases a severe cold spell without adequate snow cover causes ground freezing to an unexpected depth. One general type of solution to this problem is to obtain access into the pipe and/or conduit which is frozen and inject heated liquid into the conduit until the frozen portion becomes dislodged of ice. Another general type of approach that has been used, particularly in the case of metal underground pipes, is to apply a very high electrical current to the metal pipe casing thereby heating it to a temperature which causes the interior to become thawed. A third general type of solution to this problem has been to insert heating pipes into the ground itself and thaw the ground surrounding the pipe thereby thawing the interior of the pipe. A fourth approach is to do nothing and suffer through the inconvenience of lost utilities until the inclement weather has passed. The present invention is directed to the third type of solution, at least with respect to the problem of thawing frozen underground pipes.
A further problem exists in connection with outdoor construction projects in cold climates. For example, construction work such as brick laying is severely hampered in cold weather, not only because the concrete tends to be difficult to maintain in usable form, but also because the sand mixtures and the bricks themselves tend to become frozen. The optimum temperature for laying brick or block materials is in the range of 40.degree. to 45.degree. F. If the temperature drops below this range, the mortar used to bond the bricks and/or blocks will not properly adhere to the materials leading to a weakened structure. In such situations it would be helpful to elevate the temperature of such construction materials so as to improve the overall quality and efficiency of the finished construction project. The present invention is also useful on construction projects for heating construction materials in preparation for use.
In the past a problem has arisen concerning circulation of heated fluid in the vicinity of the closed penetrating end of the probe. Various mechanical solutions have been implemented to improve fluid circulation within a probe, including the use of a perforated inner tube. The use of a perforated inner tube, and/or other complicated mechanical solutions to improve heated fluid flow within a probe, significantly increases the expense of the mobile heating system.